1. Field of the Invention
The present invention relates an outboard motor especially having an improved structure of an oil cooler.
2. Description of the Related Art
An outboard motor includes an engine, particularly of an internal combustion engine, in which many slidable elements and rotatable elements are arranged. In view of this matter, a lubricating device is used in combination with the so as to supply lubricant oil to respective elements of the engine so as to reduce frictional resistance in the respective elements under a function of the lubricant oil to thereby achieve an adequate performance of the engine of the outboard motor.
There also exists an engine of the outboard motor provided with an oil cooler for cooling lubricant oil, taking into consideration the fact that increase in temperature of the lubricant oil deteriorates its lubricity.
In a conventional four-stroke-cycle engine mounted with an outboard motor, no engine is provided with a water-cooled (water-cooling type) oil cooler which is provided separately from the engine.
However, since the engine of the outboard motor is surrounded with an engine cover, i.e. cowl, it is made difficult to place such an oil cooler and its accessories in a space between the engine (engine body) and the engine cover.
Moreover, in a case where sea water is utilized as cooling water in the water-cooled oil cooler, if the cooling water (i.e. the seawater) is left as it is stored in the oil cooler, the oil cooler may be clogged with salt, thus being troublesome.
An object of the present invention, which was made to solve the above-mentioned inconveniences, is to provide an outboard motor having an improved structure of an oil cooler and its mounting structure so as to make it possible to place an oil cooler in a permissible small space and improve serviceability thereof.
This and other objects can be achieved according to the present invention by providing an outboard motor comprising:
an engine having a crankcase in which a crankshaft extends perpendicularly in a state of an outboard motor mounted to a hull;
an engine cover in which the engine is arranged;
an engine holder disposed below the engine;
a drive shaft housing which is disposed below the engine holder and in which a drive shaft connected to the crankshaft extends vertically;
an intake device including an intake manifold disposed to a side surface of the engine;
a lubricant supply device for supplying lubricant oil to the engine;
an oil filter disposed below the intake manifold and adapted to filtrate lubricant oil; and
an oil cooler arranged below the intake manifold and between the engine and the oil filter.
In preferred embodiments of the above aspect of the present invention, the oil cooler has a cooling water inlet formed to a lower portion of the oil cooler and a cooling water outlet formed to an upper portion of the oil cooler.
An up-streaming passage may be further disposed on an upstream side of the engine, through which the cooling water for the oil cooler is introduced. The up-streaming passage is formed to the engine holder.
A down-streaming passage may be further disposed on a downstream side of the engine, through which the cooling water after passing the oil cooler passes.
The cooling water for the oil cooler is introduced from an upstream side of an engine cooling system and the cooling water after cooling the oil cooler is guided to a downstream side of the engine cooling system.
The oil cooler is provided with a water drain port, which is disposed to a portion corresponding to a full tilt-up angle of the outboard motor.
The oil cooler comprises a casing and a cooler body disposed inside the casing, and the casing is formed with a cooling water flowing-in union and a cooling water flowing-out union disposed in correspondence with the cooling water flowing-in union. The cooler body may be provided with a cooling member which is composed of a plurality of fins formed on an outer surface of the cooling member so as to be in parallel to each other from an outer surface of the cooling member in a direction perpendicular to an axial direction of the cooling member. The cooler body has a cooling member provided with an oil gallery to which the lubricant oil is guided, and a water gallery to which cooling water is guided is formed between the cooling member and the casing, the oil gallery and the water gallery being water-tightly sealed by sealing means. The sealing means includes a first sealing member disposed to joining surfaces between the cooling member and the engine and a second sealing member disposed to joining surfaces between the cooling member and an end wall of the casing on the side of the oil filter, the cooler body is fastened to the engine by means of stand bolt, which is screwed into the engine, so as to come the cooler body into a liquid-tight contact to the engine through the first sealing member, and the casing is urged against the cooling member by screwing the oil filter to the stand bolt so as to hold the end wall of the casing between the cooling member and the oil filter through the second sealing means. Preferably, both the first and second sealing members are O-rings.
The cooling water flowing-in union is provided on a lower portion of a side wall of the casing and the cooling water flowing-out union is provided on an upper portion of the side wall of the casing so as to be opposite to each other.
According to the outboard motor of the above aspects of the present invention, it is possible to provide a simple and compact structure of the outboard motor, dispose the oil cooler in a limited space around the engine, and reduce the number of parts for the outboard motor and simplify the assembling operation of the parts.
In addition, it is possible to provide an effective cooling property of the lubricant oil with the simplified structure and the minimum number of the parts as reduced.
Furthermore, it is also possible to carry out an easy disassembling and maintenance operation of the oil cooler and prevent the oil cooler from being clogged with salt.
The natures and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.